Interpretive Summary: High productivity agriculture exacts a high cost in terms of energy and our environment. A less costly and nondestructive means for achieving the same goal rests on the establishment of a viable low-input farming system. However, to implement such a plan we must develop plant systems that can efficiently scavenge and utilize soil nutrients at low levels. Fungi known nas arbuscular mycorrhizal (AM) fungi colonize, or invade plant root cells, establishing a symbiotic relationship. In this mutual association these fungi hasten plant growth, and improve stress resistance by increasing the root mass to facilitate the transport of needed nutrients to the plant cells. Since mycorrhizal fungi are obligate symbionts (require the presence of a plant root for development) they normally cannot grow unless a root tissue is present. On the other hand a closely related fungus an, ectomycorrhizae is capable of completing its life cycle in the absence of a ahost plant. However it is not known what factors are responsible for allowing these species to live in a free state. In this study we examined different metabolic events in the life cycle of the ectomycorrhizal fungus, an edible mushroom, Cantharellus cibarius to determine what possible biochemical mechanisms set it apart from AM fungi in its ability to complete its life cycle. One significant difference that we found in ectomycorrhizae is that it processes photosynthetically derived carbon differently. This finding brings us one step closer to ascertaining the essential factors required for the eventual production of AM fungi in pure culture and its field application as a "biofertilizer".

Technical Abstract:
(13)C-NMR analyses of cantharellus cibarius growth media were made. We found exudation of trehalose and mannitol which may explain the observed phenomenon of reproducing pseudomonas bacteria inside fruiting bodies. Exudation varied with strain and environment. NMR analyses of stored (13)C was also performed. Trehalose, mannitol, and arginine were revealed. .The mannitol pathway seems to play an important role for trehalose production in this species unlike the AM fungus. This is the first study of the fate of the photosynthetically derived carbon in edible ectomycorrhizal mushroom cantharellus cibarius.